Harmon PB-105 parallel installation

[AlaskaHybrid]

Well, I'm happy as a clam. Installed my pellet boiler in parallel with my existing Energy Kinetics oil fired boiler this past October. Supply and return piping, two check valves and one wire connect the two. When the pellet boiler comes up to temperature the control relay changes the circulator from oil to wood and the oil boiler is strictly standby with the EK energy manager controlling zones via the thermostats. I figured 17 tons to take me through the Fairbanks winter and it's looking like a pretty accurate estimate. I heat 2/3 of 5,000 sq ft with a pellet stove insert and the basement 1,800 sq ft with the boiler. The upper two floors have inefficient home brew radiant floor zones installed by the home's designer and the basement is hot water baseboard with a unit heater in the workshop. I'm heating one radiant zone that is a bit too far from the pellet stove to be comfortable. We consulted Energy Kinetics for the marriage of the two and they provided excellent support. The oil boiler has run just a tick over 24 hours since October 24th, a mere fraction of the time it would normally run over the winter. I've also added the Harmon 3/4 ton bulk hopper. We averaged a ton every 10 days or so during the peak heating days. If there is any interest I'll post photos and diagrams and entertain questions. I'm not an expert but I'm learning fast.

 

[velvetfoot]

Wow, 17 tons!

 

[AlaskaHybrid]

Yes. I ran the numbers by averaging the gallons of oil used over the last 9 years prior to installing my pellet stove insert and using the the average cost of the last 7 fill ups. I figured the BTU value of oil and converted that to equivalency for pellets. I'm currently on ton #15 so may beat that number by a little (global warming is real!). Even at $242/ton I still beat the price of oil heat by over $3,300 a year.

 

[velvetfoot]

Looking at the avatar picture, you get bulk delivery to that pellet bin? How much does that hold, and did you build it yourself?

 

[AlaskaHybrid]

It holds 3/4 ton but bulk delivery is not cost effective at that size with the delivery fee tacked on. It is manufactured by Harmon and is shipped partially assembled. I assembled it in an evening. I've had to design a shaker motor and wire it to the auger motor so that when it runs it vibrates the hopper otherwise about 3-4 bags worth will be left in the bottom of the hopper when it quits feeding (looks like an ant lion trap). I like it a lot despite having to give up the space to house it. You have to be a bit of a handyman to install it as it requires modification of the stove hopper to install the feed tube and sensor. I'll try to upload a photo or two of my installation. Mine is placed on the cleaning rod side with enough clearance to get the ash pan out. I had to raise it about 9" off the floor to get the angle right on the feed tube to keep it from clogging.

 

[velvetfoot]

Hi again. Could you possibly post a diagram of your parallel hook up? Thanks.

 

[AlaskaHybrid]

Here are the drawings from Energy Kinetics. The principles are pretty straight forward and should be able to be adapted to other manufacturers. This is the electrical diagram. The control relay notifies the energy manager to shut off the circulator on the EK2000 and simultaneously starts the circulator on the pellet boiler. This somehow also disables the burner on the oil boiler. I don't use a dump zone on the pellet boiler. I have a UPS wired to a power failure relay (diagrams provided by Harmon) on the pellet boiler to keep the combustion blower going long enough to let the fire go out.




The plumbing connection shown below is very simple using two flow checks. My systems are connected together with 1-1/4" copper. I had to insulate the lines with rigid fiberglass insulation because the garage got way too hot with all that exposed copper shedding heat.

 

[AlaskaHybrid]

I actually used just over 16 tons last winter. When I shut everything off this spring I had 41 bags left over from the 17th ton. The fuel truck delivered 23.8 gallons of fuel oil in June. My total oil bill was less than $90 for the year. Typical fuel cost was about $7500/year (average of 2045 gallons). I spent $4114 on pellets. I can live with those numbers!